Patient Information - Carotid Artery Surgery
INDEX - click on the following to
|what is a carotid artery ?||treatment of TIAs|
|what can go wrong ?||carotid endarterectomy|
|transient ischaemic attack (TIA)||surgery for stroke|
|rapid TIA investigation||future possibilities|
|carotid duplex scanning||carotid artery pictures|
Each person has two carotid arteries, one on either side of the neck. You can feel the carotid artery pulsating if you place your fingers just behind and to one side of the Adam's apple in the neck. The carotid arteries supply blood to the brain and originate inside the chest from the main artery coming directly from the heart (the aortic arch). There are also two smaller arteries at the back of the neck (vertebral arteries), one on either side, which supply a smaller amount of blood to the brain. They can become more important if, for any reason, the carotid arteries become narrowed or blocked. The vertebral arteries are seldom narrowed by hardening of the arteries (atheroma) but can be pinched by arthritis in the neck (vertebrobasilar insufficiency).
The arteries on the left side of the neck mainly supply blood to the left side of the brain and vice versa. There is, however, some cross flow between left and right arteries within the brain itself. The left side of the brain controls movement and feeling in the right side of the body and vice versa.
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what can go wrong ?
Hardening and narrowing of the arteries (atheroma or atherosclerosis) is a disease of all the arteries in the body. It can cause heart attacks by narrowing the coronary arteries, poor circulation in the legs, or strokes by narrowing the carotid arteries. Atheroma is caused by a combination of various factors including smoking, high cholesterol, obesity, lack of exercise and family history. All the arteries of the body can be affected but, in most patients, one area alone predominates. Most patients with moderate atheroma of the carotid arteries have no symptoms and the brain adapts to the slight reduction in blood supply by compensatory enlargement of the back up (vertebral) arteries.
Narrowing, roughness and irregularity of the inside of the carotid artery , as a result of atheroma, can allow the accumulation of blood clot and debris which may break off into the blood stream and interrupt blood supply to various areas of the brain. This may cause either temporary symptoms or a permanent stroke (see Transient Ischaemic Attacks and Strokes in the index).
Complete blockage of a carotid artery may occur without any symptoms if the brain's blood supply can be maintained by the other blood vessels. However, in certain patients, blockage of a carotid artery causes some areas of the brain to be deprived of an adequate blood and oxygen supply and a permanent stroke may result.
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transient ischaemic attacks (mini-strokes or TIAs)
A small blood clot or debris from a diseased carotid artery can detach from the artery and shoot up to lodge in one of the small arteries in the middle of the brain. This causes results similar to a stroke - paralysis or loss of sensation in the arm, leg or face on one side only . Sometimes the speech is affected. Usually the blood clot or debris breaks up rapidly or is dissolved by substances made in the blood system and all the symptoms disappear within a matter of a few minutes to a few hours. By definition, after a TIA, patients return completely to normal within 24 hours.
Occasionally the blood clot lodges in the main artery which supplies blood to the eye. This results in a temporary total or partial blindness in the affected eye (amaurosis fugax)
People who have a ministroke or TIA are at risk of further major strokes and should consult their General Practitioner. The risk can sometimes be reduced by surgery to unblock the carotid artery (carotid endarterectomy).N.B. Symptoms unlikely to be caused by ministrokes or TIAs include memory loss, dizziness, blurred vision (particularly if in both eyes), fainting episodes or general collapse.
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A stroke may occur when the blood supply to an area of the brain is cut off by a blood clot from the carotid artery which then does not dissolve. Alternatively the carotid artery itself may become completely obstructed by blood clot. In this situation, the area of the brain supplied by the blocked artery dies and any disability which results is more permanent, although there is often some improvement in the first few months after a stroke. Strokes are very variable and can be quite mild (slight weakness or speech impediment) or severe (total paralysis down one side, loss of speech). Severe strokes can be fatal. Patients who have a stroke need specialist care, often in hospital. A general practitioner will usually arrange treatment and follow up. In most patients, carotid surgery has no role to improve the circulation once an area of brain has died.
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What to do about TIAs: the evidence.
In the last 10 years, several large clinical studies have been done which help doctors provide a logical management for patients who have carotid artery disease.
(a) Trials of aspirin. In the 1980s, a large trial run by the Medical Research Council showed that patients who were treated with a low dose of aspirin every day after a TIA were less likely to develop a stroke subsequently. Aspirin works by blocking the action of platelets, one of the constituents of blood which are responsible for forming blood clots. Aspirin makes platelets less sticky and reduces the chance of blood clots forming in the carotid arteries and causing TIAs and strokes.
All patients who have a TIA or stroke should be treated with low dose aspirin regularly for life. All doses from 75mg per day (junior aspirin) up to 300mg per day are effective. Aspirin can cause ulcers in people with a sensitive stomach.
(b) Trials of carotid surgery. In the early 1990s, two big studies, one in Europe and one in North America, compared unblocking the carotid artery surgically (carotid endarterectomy) with aspirin treatment alone. In patients who had a TIA, aspirin treatment alone was associated with a risk of about one in three of developing a subsequent stroke over the next few years. The operation carotid endarterectomy significantly reduced the risk of stroke in patients who had suffered a TIA , but only if there was a tight narrowing of over 70% in the carotid artery supplying the affected side of the brain. In patients who had a TIA but whose carotid artery was less than 70% narrowed, surgery did not have any advantage over aspirin treatment.
After a TIA the risk of further stroke is highest in the first month or two. It follows that it is vital to find out as quickly as possible in any patient who has a TIA whether they have a tight narrowing in the carotid artery. These are the patients who, as vascular surgeons, we can help the most. To help find out as soon as possible, the vascular surgeons in Gloucestershire have developed a fast track carotid scan service.
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Rapid TIA investigation
service (information circulated to all local GPs)
In an attempt to speed up the diagnosis of carotid artery disease and identify patients in whom timely carotid surgery may prevent a stroke, the Gloucestershire Vascular Group has established a Rapid TIA investigation service. The following information has been circulated to all General Practitioners in the area:
Gloucestershire Vascular Group
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Carotid duplex imaging.
The carotid arteries can be visualised simply and painlessly using a modern ultrasound scanner called a duplex. This is done in the vascular laboratory as an outpatient procedure and takes about 30 minutes. Clear pictures can be obtained by running a small scanner over the neck. By this means it is usually possible to tell whether the carotid artery is widely open or narrowed. Using computer analysis it is also possible to assess the degree of narrowing (stenosis). The technician who performs the scan will send a report to one of the vascular surgeons and alert him particularly if the artery is more than 70% narrowed. Remember that the carotid artery on one side of the neck supplies blood to the brain which controls the opposite side of the body.
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The operation. The aim of the operation of carotid endarterectomy is to clean out the atheroma (hardening of the arteries) which was narrowing the artery, leaving it widely open to supply blood to the brain. Cleaning the inside of the artery reduces the risk of further blood clots forming in the artery which can detach and pass into the brain to cause a stroke.
The operation may be done under a general anaesthetic (patient asleep) or occasionally under local anaesthetic (patient awake but skin and tissues made numb by injection). The artery is identified through a vertical cut in the neck. The artery is temporarily clamped so that it can be opened and cleaned out, Some patients have a plastic tube shunt inserted into the arteries above and below the operation, through the same wound, to maintain blood flow to the brain whilst the artery is clamped off. Others have sufficient flow through the opposite carotid artery to make this unnecessary as the blood flow inside the brain can cross over. Some surgeons repair the artery with a patch of artificial material to widen it and improve blood flow. ( pictures of carotid surgery).
After the carotid artery has been repaired, the skin is closed, usually with dissolving stitches. A small plastic tube drain may be left under the skin to prevent a bruise forming (haematoma).
Risks of carotid surgery. Operating on the carotid artery can be dangerous. Up to 5% of patients can have a major complication which may be fatal. The biggest risk is of a stroke, the very condition the operation is designed to prevent. The main risks are on the day of operation. To try to reduce the risk all patients have very close monitoring during and after surgery. Blood pressure and pulse are regularly observed, usually by machine. Blood flow through the brain may be monitored using a transcranial Doppler. Most patients are observed for at least 24 hours in a high dependency or intensive care unit. Vascular surgeons are continually checking their surgical and monitoring techniques to minimise the risks of carotid endarterectomy. The risk to each patient is different and a vascular surgeon will discuss individual problems with each patient before operation. Occasionally, an opinion about the state of a patient's health may be sought from an anaesthetist preoperatively.
Outcome Although carotid endarterectomy is a major and risky operation, once it has been completed successfully the risk of a subsequent stroke is about 1% per year (significantly less than the 7.5% per year on aspirin). Most patients only need 2 to 3 days in hospital. Convalescence takes about one month after which all normal activities (including driving) may be resumed safely. It is beneficial to continue low dose aspirin therapy, if possible, for life.
The main problems after operation are sore throat and neck which can usually be eased by simple painkillers. The neck skin has an excellent blood supply so the wound often becomes quite swollen and bruised. This usually settles in a couple of weeks. Often there is a patch of numbness around the cut in the neck which may persist for some months but eventually resolves. More permanent nerve damage is fortunately very rare.
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Carotid endarterecomy for stroke.
Unfortunately it has never been possible to demonstrate that performing an emergency carotid endarterectomy helps a patient who develops an acute stroke. When a completed stroke causes part of the brain to die, restoring the circulation to that part of the brain seems to cause more damage still. However, if a patient makes a good recovery from a stroke and is then shown still to have a narrowing of over 70% in the carotid artery supplying that side of the brain, carotid endarterectomy has been shown to reduce the risk of a further stroke. Surgeons usually prefer to wait 6-8 weeks after completed stroke before doing a carotid endarterectomy, and the risks are slightly higher than in patients having carotid endarterectomy for TIA. Any patient who makes a full recovery after a stroke and who is young and fit enough for surgery should have a duplex investigation of the carotid artery. If a significant stenosis >70% is shown in the relevant carotid artery a vascular surgical opinion should be sought.
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Carotid angioplasty. Angioplasty is the use of a balloon to stretch up a narrowed artery. A deflated balloon is passed through the skin up the inside of an artery and positioned at the site of a narrowing. The balloon is inflated and the narrowing dilated. Angioplasty of coronary and peripheral arteries is performed routinely in many hospitals. It had been thought that carotid angioplasty would be risky and more likely to cause a stroke than prevent one. A recent preliminary study, however, has shown similar rates of success for both carotid endarterectomy and carotid angioplasty. Whilst this study needs repeating on a larger scale, carotid angioplasty may well become a more routine procedure over the next few years.
Carotid surgery for asymptomatic stenosis. There is also a risk of stroke in people who are found to have a tight narrowing in a carotid artery who have not had any problems such as TIA or ministroke (asymptomatic stenosis). However, the risk of future stroke is much less than the 7.5% risk in similar patients who have had a TIA. Several studies have compared whether it is safer to treat people with a symptomless stenosis by carotid endarterectomy or aspirin alone. Although two studies have shown that the risk of future stroke is less after carotid endarterectomy than after aspirin alone, the risks are much less significant than in patients with symptoms. Approximately 40 patients need to have surgery to prevent a single stroke, compared to five operations in symptomatic patients. Once again there are studies under way to determine finally how patients with a symptomless narrowing of the carotid artery should be treated and the answer should be clearer within a few years.
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If you need any more
information about carotid disease or surgery please contact
your General Practitioner or one of the Vascular Surgeons
in the Gloucestershire Vascular Group
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view carotid artery pictures
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This page compiled by Jonothan Earnshaw DM FRCS
on behalf of the Gloucestershire Vascular Group